1. Field of the Invention
The present invention relates to a friction mechanism, in general, and to a stepless free-wheeling wrench with thumb actuated reverse mechanism, speed-wheel, and socket release, in particular.
2. Description of the Prior Art
Reversible socket wrenches have been known for some time. Typically, such a wrench consists of a main body portion containing a long handle for effective leverage in turning. In terms of a generalized description of a friction movement, this could be considered as the driving member. Mounted for rotational movement about its axis within the body of the driving member is a tang assembly which may be considered as the driven member. Typically, through a ratchet and pawl mechanism or, more recently, a stepless torque mechanism, a manual force applied to the handle of the wrench is transferred through the wrench body to the tang assembly, the end of which receives a socket or fixture for turning a bolt, screw, fastener or the like. Provision is made within the wrench so that a clockwise or counterclockwise turning of the fastener may take place. When a stepless torque mechanism is employed, the reversible socket wrench makes use of a friction wheel forming part of the tang assembly. The friction wheel is variously advanced by a plurality of rollers or cams, which, when biased by a spring force, are propelled by friction up an inclined plane or arc, providing a wedging action to increase the frictional force necessary for the desired torque. When either the driven member or the driving member is reversed, the cams or roller members are forced down the inclined plane by friction, thus, releasing the wedging force and allowing free-wheeling or overrunning action to occur. This mechanical movement is commonly known as a free-wheeling or one-way clutch. Socket wrenches employing such a structure operate successfully for very light torque applications when placed in a space envelope common to typical ratchet wrenches. But, when required to produce tortional forces of 200 to 400 foot pounds, which are typical of present ratchet wrench capabilities with a 1/2 inch square tang drive, internal forces are generated that stress the internal mechanisms and wrench housings of prior art instruments beyond their elastic range, thus, rendering them useless for further work. In addition, an even more serious problem occurs at much lower torques, that is, deflection of the loaded members causes the rollers or cams to stick in the driven position; thus making it difficult, if not impossible, to shift a device into the direction reversed from the last applied torque.
Most prior art stepless wrenches require two hands to shift the mechanism to the reverse driven direction. In addition, when a speed-wheel for spinning down loose fasteners is employed, the speed-wheel is usually inconveniently located at the point where the socket or fixture is secured to the tang in close proximity to the wrench body.
Many of the prior art reversible socket wrenches employ various methods to secure the socket to the wrench square drive tang. Among the known methods is one that employs a snap-on ball detent means, which works very well when attaching the socket to the wrench, requiring only a firm push to engage the socket with the drive tang. However, removing the socket with greasy hands is very difficult and sometimes impossible.
One prior art wrench has provided a convenient method of releasing the socket. However, the device requires a release button to be pushed in order to engage the socket, which is an inefficient trade-off. It is, therefore, desirable to provide a mechanism which will allow the socket to be simply pushed into position with relatively low force, while requiring relatively high force to pull the socket off the tang prior to pushing the release button.
The present invention is directed toward eliminating many of the aforementioned problems associated with the prior art devices by providing a reversible ratchet-like wrench which will advance a fastener in the desired direction with very slight motion of the handle, requiring much less motion than is typically necessary of common fine-tooth ratchet wrenches, thus, providing the ability to tighten a fastener in areas where clearances for handle motion are restricted to 1.degree. or 2.degree. of arc. The reversible ratchet-like wrench of the present invention also contains a speed-wheel conveniently located for rapid spin-down of fasteners, a switch for reversal of the wrench's free-wheeling action, and a novel socket release mechanism, all of which can conveniently be operated with one hand with all of the functions accomplished by thumb actuation. The improved wrench of the subject invention also employs a unique stepless torque mechanism which allows the radius of the head of the wrench to be no greater than commonly found on popular ratchet wrenches.